Interlocking system for railroads



13% 1941- N. D. PRESTON INTERLOCKING SYSTEM FOR RAILROADS Filed Jan. 5, 1938 8 Sheets-Sheet l Dec. 9, 1941. N. D. PRESTON -INTERLOCKING SYSTEM FOR RAILROADS 8 Sheets-Sheet 3 Filed Jan. 5, 1958 Dec. 9, 1941. N. D. PRESTON INTERLOGKING SYSTEM FOR RAILROADS 8 Sheets-Sheet 4 Filed Jan. 5, 1958 9 1541. N. D. PRESTON INTERLOCKING SYSTEM FOR RAILROADS Filed Jan. 5, 1938 8 Sheets-Sheet 5 zmnzu E2 E3 E2 0 man T HMUQ Dec. 9, 1941. N. D. PRESTON INTERLOCKING SYSTEM FOR RAILROADS a Sheets-Sheet e Filed Jan. 5, 1938 INVENTOR QQE J H I HHH Dec.-9, 1941. N. D. PRESTON INTERLOCKING SYSTEM FOR RAILROADS 8 Sheets-Sheet 7 .ocd in? 0Q Dec. 9, 1941'. N. D. PRESTON INTERLOQKING SYSTEM FOR RA'ILROADS a Sheets-Sheet 8 wm 3 zm $7 r r m 20.7

Emmi T I INVENTOR JII E r it 5 T E z r i f Filed Jan. 5, 1938 Patented Dec. 9, 1941 Neil? 11. Preston, Rochester, N.

General Railway Signal Company,

Y., assignor to Rochester,

Application January 5, 1938, Serial No. 183,499

45" Claims.

This invention relates to a systemior; control-.- ling the operation. of power-operated: track switches andthe. indications of; the signals for a: trackzla'yout at terminals or the like on railroads, and more particularly'to a system of the type called an-entrance-exitlor NX system.

Insthe entrance-v-exit type of; switch and signal control system, to; which the present invention more particularly relates; the" desired operation of? the various track switches tothezposition required: to set ups the various routes through the track: layout and; thecontrol of? the clearing of the signals. are accomplished by actuating manually operable buttons or likeidevicesassociated with the entrance and: exit ends of? the routes for train movement: through. the track layout from one signal to another signal in advance governing. train movement in thesame direction. In: other words,rin:- accordance with the operating principles of; the entrance-e'xittypa ofswitch and signal controllsystem, as distinctivefrom the ordinary: unit-clever type, the operatormay position all: oi the switchesifoir a. desired route andv control, the clearing of; the signal fortrain movement. in one direction or the other by merely operating a button: belonging to thezentrance end of? that desired route and then a button atzthe exit endq: and a suitable organization of relays and; circuitsrespondato; such joint actuation of these two buttons atltheentrance and eXit ends of the desired route t'ov cause all of: the track switches or crossovers involved to assume the normal orireverse.pjositioniasyrequired and also to control: the clearing" of the: s'ignalrfortrain movementi from the entrance end to the exit end of; that route. In the preferred arrangement, these buttons are located; adjacent, the: points on aminiaturetrack:- diagram' of the; track layout on; the control panel: which correspond: with; the signal locations constitutingthe: entrance orexit ends-'for'thevvarious routes.

A -switch' andisignal. control system: of thisentrance-exit type is disclosed, for example,- in? the priorapplication of: S. N: Wight; Ser. No. 69905, filed: March 20, 193.6, and lathe-prior applica.- tion of A. Langdon, Ser. No. 119,641, filed'IJanucry 8,; 1937'. The'present invention: is in'the nature of a modification or improvement, in the means employed in: these. and. other prior applir cations: for. accomplishing the desired functions and: results inzsuch a type of system; and no claim is made herein to anything disclosed, in such prior; applications;

In; the organizationsi heretofore pr p s d f r performing? the entrance-exit function s parate entrance and" exit buttons are employed; for the endsof the routes, and one or the other, or both, of these buttons is of a type which remains in its operation untilrestored manually. One object of the present invention is'to provide an improved organization of relays and circuits in a systemof this entrance-exit type in which a single,selfrestoring push button is all that is needed; for each signal location constituting either the entrance or-eXit point: for a route or routes, even for adouble signal location. The same button acts at different'times to perform the function of an entrance buttongoran exit button as the case may be, dependent upon the actuationof other buttons; andthe direction of train movement over the given route is determined by the sequence or order in which the buttons for the ends; of that route are manually actuated. In the; case of a double signal location, constituting both the entrance: end and the exit end, of various' routes for train movements in both directions, the single button at such location serves to perform the entrance iunctionfor either direction of; train movement away from such double signal location and also the exitfunction for. train movement inyeithen directiontoward such location;

Generally speaking, and without" attempting to define the nature or'scope of'the invention, this object; is attained by'providing means so that;

with the system in a normal condition, the first button actuated acts to perform the entrance function and renders all other buttons ineffective to actas entrance buttons, this condition persisting until another button for the exit end of an available route belonging. to the first button is actuated toestablish such route, whereupon the system is restored'to its normal condition ready for the next operation of setting up a route by the joint and sequential actuation of two buttons belonging to the entrance and; exit ends of an available route.

Another object-of the invention is to provide what may be termed a series route. circuit network as a means responsive to the joint and; sequential actuation ofthe buttons at theends of a given route to provide for the proper; control of all of the switches involved in that route by energizing suitable normal or reverse switch control' relays for each-of said switches or crossovers. Generally speaking, the circuit network contemplated by this invention may be said to comprise feed points one for each signal location; and when, operating potentials" are applied to .those feed points of: the network. corresponding, with the ends of the route defined by the buttons actuated, the normal or reverse switch control relays in that route are energized in series, rectifiers being included in certain portions of the network to block the flow of current through normal or reverse switch control relays for abnormal or alternative routes that would otherwise occur on account of the connections in the network required to energize the switch control relays for the desired routes. In this network, the energizing circuit for each normal switch control relay includes a back contact of the reverse switch control relay of the corresponding switch or route manipulation is helpful to the operator. It is considered that the through routes for the ordinary track layout for terminals, junctions, and the like, which can advantageously be established by actuation of the buttons at the extreme ends thereof are ordinarily limited to a few main routes and less than the possible number of through routes. Generally speaking, a through route relay is provided at the intermediate signal locations selected, and. this relay responds to the actuation of the buttons at the extreme ends of crossover, and similarly the energization of each reverse switch control relay is dependent upon aback contact of the corresponding normal switch control relay, so that the complete series route establishing circuit for each route is interlocked with the route establishing circuits of all other conflicting routes. Consequently, whenever any given route is set up by the joint and sequential actuation of the associated buttons, no other route in conflict therewith may be set up by the actuation of other buttons, but parallel or nonconflicting routes may be established, such interlock being obtained in a simple way by the interlock of the control relays for individual switches.

- Another object of the invention relates to those situations where optional or alternative routes between common entrance and exit points are provided by the track layout. In accordance with this invention, a separate optional route lever is provided in such cases to select between the optional routes, the route establishing circuit network being arranged so that with this lever in one position one of the optional routes is always obtained by the actuation of the corresponding entrance and exit buttons, and with this lever in the other position, the other of the optional routes is always obtained by the actuation of these same buttons. Provision is also made so that, if the preferred route corresponding to the usual position of the optional route lever is not available by reason of the establishment of another route in conflict therewith, the other inferior route will be automatically established by actuation of the corresponding entrance and exit buttons without changing the position of the optional route lever. In other words, it is contemplated that the selection be tween the optional routes will be under the manual control of the operator, as well as automatically depend upon conditions existing at the time the buttons for the common ends of the optional routes are actuated.

Another object of the invention is to organize the route establishing circuit network in such a way that certain through routes may be established over certain portions of track between signal locations in end-to-end relation past one or more intermediate signal locations by manual actuation of only the two buttons at the extreme ends of such through routes, at the same time permitting the routes for each of said portions of track between adjacent signals to be set up individually for either direction of train movement by the actuation of the corresponding buttons. In accordance with this invention, it is proposed to provide for such end-to-end or through route operation by means of a separate and additional circuit organization, to be used where desired, so that the through route operation is effective for only those possible through routes of the track layout where the through the through routes or portions thereof past such intermediate signal location, and acts to produce the same controlling eifect upon the route establishing circuit network at the point corresponding with such intermediate signal location as if the button therefor had been manually actuated.

Other objects and characteristic features of the invention relate to the means employed to enable the operator to cancel the setting of a route set up prematurely or by mistake by operation of a special cancel key in conjunction with the actuation of the button at the entrance end of the route to be cancelled; to provide for individual operation of any switch by manipulation of a separate auxiliary or emergency switch control lever; and to make provisions for the display of suitable and desirable visual indications of switch position, track occupancy, routes proposed and established, and signal clearing in a distinctive and arrestive manner on the track diagram to furnish the operator with the necessary information for the proper and eficient manipulation of the system.

The nature of the invention and the complexity of the structural organization and mode of operation makes it difiicult to define the invention completely and yet briefly; and various other characteristic features, attributes, and ad vantages of the system embodying this invention will appear as the description progresses.

The accompanying drawings illustrate conventionally and diagrammatically certain specific embodiments of the invention applied to typical or representative track layouts, the parts and circuits being illustrated in a manner to facilitate an explanation and an understanding of the invention, rather than to show specifically how the various relays and devices might be arranged and structurally organized in practice, various symbols and nomenclatures being employed to simplify the illustration.

Fig. 1 shows diagrammatically a portion of a control panel, with its track diagram and associated buttons, for a relatively simple track layout typical of the arrangements of signals and crossovers found in practice, together with the entrance and exit relays responding to the actuation of the buttons, and the relays, circuit connections, and rectifiers constituting the route establishing circuit network for governing the energization of the normal and reverse switch control relays, and also one typical application of the principles of selection between optional routes both automatically and by an optional route lever.

Fig. 2 illustrates another track diagram and route establishing circuit network for another typical track layout involving two possible routes between common entrance and exit points, where one of these routes is a run-around movement over crossovers that is abnormal and not desired, this figure illustrating particularly how rectifiers are employed in accordance with this invention to avoid the flow of current in a series network that would otherwise give such an ab= normal or undesired route.

Fig; 3 illustratesasimple. embodiment oflcontrol circuitssuitable for governing the operation of a switch machine and its associated signals by' the normal and; reverse switch control relays and the entrance and exit relays of the route establishing circuit network.

,Fig. 4 illustrates typical control circuits for the signals of a track layout like that of Fig. 1.

Figs. 5A and 53', adapted to be arranged endto-end, illustrate the organization of relays and circuits suitable for governing the entrance and exit relays at a double signal location by the operation of a single button, and a typical application of through route relays and their associated circuits for through routeoperation.

Fig. 6 illustrates diagrammatically the way in which the track diagram is preferably arranged to provide for the display of visual indications for the information of the operator.

Figs. 7 and 8 are fragmentary sections of the control panel to illustrate one typical construction for providing" the desired visual indications.

Fig; 9 is a diagrammatic showing of the control means for the lighting circuits for the indicating" lamps; and

Fig. 10 is a diagrammatic illustration of the circuits for goveming' the operation of certain east and west directional stick relays employed in the control of the switch control relays and the visual indications on the control panel.

General organization of the system-In accordance with this invention,- it is contemplated that the various switches and crossovers of the track layout'will be equipped with a power operated switch machine in the usual manner, a switch machine of-this character being disclosed, for example,- in' the patent to W. K. Howe,-No. 1,466,903, datedSeptember 4, 1923. This switch machine is provided'with contacts, in accordance with the usual practice, which govern the energ'ization of a switch repeater or position indicating relay WP, dependent upon the position and locked condition of the'switch points.

It is also assumed that wayside signals of a suitable type will be provided at the various signal locations constituting the entrance and exit ends of the various routes through the track layout, and that these signals will be governed in accordance with usual practice to display the appropriate indications for high speed and low speed routes, in addition to the usual clear, caution, call-on and stop, indications, these indications being controlled by track and line relays,

and in accordance with the locked position of the track switches and indications of opposing signals, all in the manner characteristic of this type of system.

The, track layout is also assumed to be provided with suitable detector track sections; and it is contemplated that the various switch control circuits, in addition, to what is illustrated ,in this application, means andcircuits tojprovide detector, approach, and sectional rear release route locking, such as common in the, art and as disclosed inv certain specific forms in the prior application of A. Langdon, Ser. No. 119,641,,filed January 8, 1 937, and the patent. to O. H. Dicke, No. 2,045,900, June 30, 1936.

It is also contemplated that the. control ma'-, chine in. the tower or control oflice will be provided with a control panelof suitable construction having thereon a miniature track diagram will be supplemented by suitable ea of! the? track. layout, with lines to indicate the track railsian'cl; switch .p'oints; together with such diagrammatic: orsymbolicrepresentation of the signals, and: letters or numbers to.identify the switches, signals, and track circuits; as may be desired. Certain. features in the construction of the track diagram for the purpose of providing visual 'ind-ications will; be considered. more in de tail later.

In accordance withthis invention, the term route is used: as: applying to. the portion of track, including one or more single switches or crossovers, between a signal and another signal in advance thereof governing train movement in the same :direction. The arrangement. of switches for various track layouts for terminals, junctions, and the likeon railroads varies widely, but ordinarilycomprises duplications of typical arrangementsof single switches and crossovers connecting two or more parallel tracks; and the track layouts selected to illustrate the present invention-are typical or representative of those encountered in practice to a degree that it will'be obvious to any one skilled in the art how the principles and means constituting this invention may be' a'dapted or extended to apply to any form of track layout. Also; the arrangement and location of signals varies in practice, depending upon the particular character of the track layout"; but the embodiments of the invention illustrated and describedherein-for single and double signal locations, together with the provision for through routeoperation, are typical or represent-ative of the conditi'ons encountered in practitle.

In the following discussion, the letters A, B, C, etc. are used fo'rcorrveriience to identify the signal locations constituting the'ends of the various routes; andthemanually operable push buttons, and otherparts and relaysmore directly associated with of belonging to a particular signal location are, identified by the same prefix letter.

Control, 017%? apparatus-Referring particularly to Fig. 1", the manually operable self-restoring push buttons" for the signal locations, such as APB, are preferably located on the track diagram on the lines representing the track adjacent the corresponding signal location. In accordance with this invention, there is only one such push button at each signal location, even at a doublesigna-l location like C in Fig. 5A where signals areflprovided' for governing train movement to: and from such location in both directions; Each push button is of the springr'eturn type of suitable construction, such as disclosed for example in the patent to Merkel, No. 2,091,155, August 24, 193'].

In addition to these push buttons, an optional route lever or rotary button ORL is preferably located onthe control panel, as shown in Fig. 1,

adjacent a point readilyidentifiable by the operator as distinguishing between the two optional routes, that may be provided by the particular track layout; such as the routes from A to D in Fig. 1 by way ofthecrossover l in the reverse position; orbyway of" the crossover 2 in a reverse position. Also located on the control panel, at some" convenient place as shown, is an auxiliary or an emergency switch lever or key SML for" each of the track switches or crossovers, these levers being identified by suitable symbol-s marked on the panel with their respective switches.

The controlmachineisalso provided with three buses; designated the pick-up bus PU, the can'- cel bus CNB, and the common bus CM, for the whole control panel; and in addition to these buses, there is a group of relays Q, QP, and SL, and a cancel key CAN, likewise common to the whole panel.

Associated with each push button, such as the button APB, is an entrance relay ANR and an exit relay AXL. For the purpose of identifying these relays, the first letter A, B, etc. refers to the signal location, the second letter N or R identifies the relay as an entrance relay or as an exit relay, and the third letter R or L identifies the relay as providing for train movement to the right or left.

The operation of each track switch to the normal onto the reverse position is primarily governed by a normal switch control relay N and a reverse switch control relay R. In the case of a crossover, such as the crossover l in Fig. 1, which connects two parallel tracks over which there may be non-conflicting or parallel routes, two normal control relays IAN and [EN for the opposite ends of this crossover are employed. The switch points at the ends of a crossover may be operated from the same switch machine, or by diiierent switch machines'simultaneously controlled in the same way.

Route establishing circuit network.The control ofilce apparatus also includes a route establishing circuit network for energizing the normal or reverse switch control relays for the various routes in-response to the operation of the buttons at the ends of such routes. This circuit network may be considered as having feed points or ends, one for each signal location, and the operating potentials for the switch control relays are applied at these feed points by the operation of the entrance relays and buttons. The network comprises conducting paths or circuits, conveniently termed route establishing circuits, one for each of the routes, which energizes in series the normal or the reverse switch control relays of all of the switches involved in the corresponding route, rectifiers being included in certain circuit connections between these route establishing circuits, as explained. more in detail hereinafter, to avoid the undesired and improper energization of switch control relays that might otherwise occur in a circuit network of this character. Suitable resistances are also included in certain of the route establishing circuits to balance the total resistance in the circuits and cause substantially the same energizing current for each of the various switch control relays. Another characteristic feature of this network is that the energizing circuit for each normal switch control relay includes a back contact of its associated reverse switch control relay, and vice versa, so that the necessary interlock between the route establishing circuits for the different routes is obtained by the interlock between the control relays individual to the switches.

Operation of establishing a route.-Briefiy summarizing the general plan or scheme of operation, before explaining the circuits in detail, and assuming for example that the operator wishes to establish a route from A to C (Fig. 1), the manual actuation of the button APB at the entrance end of this desired route causes energization of the corresponding entrance relay ANR and at the same time renders the operation of any other button, such as CPB, ineffective to energize its corresponding entrance relay for the time being and until the equipment assumes its normal condition. When the button CPB for the exit end of the desired route is actuated, the particular route establishing circuit corresponding with this route AC is energized, together with the exit relay CXR, assuming that no conflicting route is set up. When the button CPB is released, the prevention means, rendering the buttons ineifective to perform an entrance function is restored to normal, and the apparatus is ready for the operation of another button to constitute the entrance end for some other route.

Considering now in detail the circuits and contacts by which this plan of operation is carried out, for convenience corresponding contacts on the buttons, entrance and exit relays, track relays and the like for different routes are given the same reference numbers. Assuming the parts in the normal condition shown, with no conflicting route established, the actuation of the button APB to set up a route originating at the signal location A, causes energization of the lower winding of the entrance relay ANR from the pick-up bus PU over a circuit which may be traced from positive through the back contact ll] of relay -SL, upper winding'of relay Q, back contact ll of relay QP, bus PU, through back contact l2 of button APB, back contact l3 of exit relay AXL, lower winding of relay ANR, back contact I4 of relay IAN, back contact [5 of relay lR, front contact I6 of the track relay ATR, back contact I! of button APB, connection to the cancel bus CNB, and through normally closed contact H! of cancel key CAN, to

Relay ANR, when thus energized is held up by a stick circuit from through its front contact 28, its upper winding, and contact 16 of the track relay ATP. and contact ll of the push button the same as in its pick-up circuit. When this button APB is released and returns to its normal position, the stick circuit for relay ANR is connected directly to through the front or normally closed contact H of this button, the front and back contacts l6 being make-beforebreak as indicated conventionally, in order that the flow of current through the relay ANR is not interrupted during the movement of the button.

At the same time that current is supplied through the lower winding of the relay. ANR, current flows in the upper winding of relay Q, so that this relay Q picks up in series with the relay ANR and at the same time. Relay Q is stuck up temporarily by a stick circuit from through back contact 10 of relay SL, lower winding of relay Q, its front contact 2 I, and back contact 22 of relay QP. The energization of relay Q and closure of its front contact 23 energizes directly the lower winding of relay QP, which sticks up from through its lower winding, its front contact 24, back contact 25 of relay SL, and contact 26 of cancel key CAN to This energization of relay QP disconnects at its back contact I! the supply of current from to the bus PU and connects this bus to and the opening of the back contact 22 of relay QP breaks the stick circuit for relay Q and allows this relay to assume its normally deenergized condition.

In this way, concurrent with the picking up and sticking of the entrance relay ANR, the positive potential is disconnected from the pick-up bus PU, and it is connected tonegative potential, so that the operation of any other button on the control panel is ineffective to cause energization iof its associated rentrance'relay, and this'condition persists untilrestoration Of'thB I'BIaYTQP, in the manner presently explained.

After the operator has thus defined the entrance point of the desired route A-C under consideration by picking up and sticking the entrance relay ANR, he next operates the button CPB for the-exittend of that :route. :closes the contact 36 of this button which would other- =wise tend to energize the entrance relay CNL from the pick-up bus PU; but this bus is now :connected to instead of ),;sothat such ienergization does not occur. The closure of the contact 30'of the button CPB, however, closes and energizes the route establishing circuit for the route A to C, which maybe traced from through front contact 3| of relay ANR, normal :switch control relay IAN for the crossover-1., backcontact 32 of the reverse switch controlree lay IR for the same crossover, a balancing resistance 33,.normal control relay ZAN for cross- .over 2, back contact 34 of reverse control relay 2R, back contact 3! of entrance relay CNL, exit relay C-XR, and contact 30 of the button "CPB, to

Thus, the two switch control relays IAN and ZAN 'for the crossovers I and 2 involved in the route A to C are energized 'inseries, together with the :exit relay CXR. The energization of this exit relay ,CXR closes its front contact 35 and establishes a shunt for the contact 30 of the button CPB, thereby holding up CXR over the :route establishing circuit after the button CPB is released.

When the exit relay CXR ,picks up, the bus CM is connected to the bus PTU through front contact 13 of the relay CXR, and contact 36 of the button; and since the bus PU isi now connected to at the front contact ll of relay QP, current flows from through the upper winding of relay QP, relay SL, bus CM, to bus PU to thereby energizing relay SL to open its back contact '25 and break the "stick circuit holding up relay QP, which is still maintained energized, however, by the flow of current in its upper winding. When the button CPB is released, and its contact '36 opens, the upper wind,- ing of relay QP .is deenergized and this relay .drops before the relay SL, which is slow rreleasing, can close its back contact 2.5 and establish the stick circuit for relay QP. When relays Q? and SL are thus both deenergized, the1parts are restored .to the normal condition, with the pickup busPU connected to ,.ready for the next operation of a button for the entrance end of another route.

If the operator, instead of desiring to :set up a routefor train movement from A to C, wishes to 'move a trainsfrom C to A, the button CPB is actuated firstand then the button APB, with'the result .that the entrance relay CNL :and the exit relay AXL- are energized along'with'the switch control relays IAN and 2AN. In this 'way, the sequence or order in which the .same buttons associated with the ends of :aroute are actuated determines'the direction .of train movement .over

' 'thataroute; and since the .same button is used for performing both the entrance and exitfunetions, rather than difierent buttons, it is not necessary to provide buttons for entrance and exit purposes which are distinguishable by their shape or method of operation, nor istthecperator so likely to make a mistake in his manipulation by :actuating an entrance button finstea'd ot exit :button, orvice versa.

" Thebperation of aestablishin'gcther routes for train :movement in either direction desired by the actuation-ofthe buttons associated with the ends :of .the routesis the same as that described 'iorttheiroute between A and 3C; and similar "ciricuits are r involved.

One characteristic .teature of the operation of setting up routes in accordance with this invention that the jfirst ibutt'on "actuated under normal conditions ":of the system defines thexeniteringlend-of the route by picking up :a corresponding entrance relay; and until an available route originating at such entrance1point is actually established by the actuation of the proper exit buttonsand the energization of an exitrelay, subsequ'ent operation of :other buttons is not of,- -fective to perform an entrance function. In other .words, a route attempted by the actuation of :a button :and the :energization of its corresponding entrance relay must be completed, ;or the entrance relay restored :to normal in the manner presently to be explained, joef ore the. entrance end for :some other route can be determined. This aprovide'sla check against careless manipulation by :theaoperator in leaving an entrance frelay energized without completing a route, and perhaps get an unexpected or .unintended route by the subsequent actuation of some other button intended for the entrance :end of another route. Suitable indications :of proposed .o'r established :routes are displayed :Im the control 'panel in the manner to be explained laterto provide athe operator with adequate information with regard itothe buttons which have beenactuated.

Another feature of the network is that the switch control relays are energized by applying a positive potential to the feed points :of the network a't one end, theil'eit :as :shown, and the other negative potential-at the other end. Consequently, the current through the N and R switch .control'relays flows in the :same direction for both directions of train im'ovemen't over a route. This permits :therelays to :be held up'by stick circuits through their upper windings in thelmanner Slater explained, and also avoids improper -energization of switch control relays by the :abn'orma'loperation of -buttons for the two entrance ends of routes (in parallel tracks, such as the buttons APB and BBB.

Each routeestablishing circuit, when energized :in the manner explained, is maintained energ ized so long :as the corresponding entrance relay is held up, which is until a train enters the route, or the entrance relay is "manually restored. In the case of the'route --A-C, for exannole, when a train enters the first track section of this route (see Fig. 4*) and deenergizes the track relay AT-Rythe stick circuit for the entrance relay is broken at the front contact 16 of this track relay AT-R. Consequently, the route establishing circuit is automatically restored by the train, and no special manipulation is required on the part of the operator to break down the route establishing circuit after the train-has accepted the signal, in order to be able to set up another route. Although the entrance relay ANR. and the exit relay are deenergized by the dropping of the track relay 'ATR, the switch control relays '-IAN and 2 A'N in the routeinquestion are held in a manner later explained until the train has cleared in turn the track sections AT and This maintainsthe etectr ic inter-locking between the cm'n'flietin'g routes and preventing what may be termed preconditioning for a route conflicting with a route while that route is occupied.

There may be cases when the entrance relay is energized by mistake for a route not available, or when a route prematurely set up should be cancelled; and the operator should be able to deenergizeany entrance relay manually. In accordance with this invention, the operatorcan deenergize any entrance relay, and also the corresponding route establishing circuit if energized, by operating the cancel key CAN to open its contact I8 and disconnect the cancel bus CNB from negative, and by also simultaneously actuating the button for the entrance relay to be deenergized. For example, if the button APB r is operated while the cancel key CAN is in its operated position, the entrancerelay ANR is deenergized, since its stick circuit through the normally open contact. II of the button is broken by the key CAN, and the stick circuit through the normally closed, contact I! of the button is broken by theactuation of the button. It can beseen that this operation willnot effect any other entrance relays that may thenbe energized,

since these otherrelays will be held up by their stickcircuits through the normallyclosed contact I! of their respective buttons. The operation of the cancel key CAN also opens at its contact. 26 the stick circuit for the relay QP, in order. that this relay may be .deenergized and restore normal conditions if the entrance relay being manually deenergized happens to be one for a route which is not available, so that the exit relay thereof cannot be picked up to drop relay QP and restore normal conditions in the usual way.

Interlock between conflicting .routes.With regard to the desirable interlock between conflicting routes, it will be noted that the route establishingv circuit for the route AC, above traced,

includes the back contact 32 of thereverse switch control relay IR, and also a back contact 34 of the relay 2R; and it will be evident that any route in conflict with the route A to C will necessarily require either the crossover I or the crossover 2 to be in the reverse position. If such a conflicting route should be set up, relay IR, or 2R would be energized and open the route establishing circuit for the route A to C. In other words,

by thus electrically interlocking the normal and a reverse switch control relays for each switch in the circuit network, the desired electric interlock between conflicting routes is obtained in a simple and effective manner. Such interlock does not prevent setting up parallel or non-conflicting routes such as B to D, for example, since the energization of relays IAN and 2AN for the route A to C will not prevent the energization of relays IBN, 3N and 2BN for the route B to C, as can be seen by tracing the circuit from the front contact 3| of theentrance relay BNR through relays IBN, 3N and ZBN, and the exit relay DXR to the contact 30 of the button DPB.

The route establishing circuit above traced for .the route A to C includes a compensating or balancing resistance 33, because this circuit in cludes only two switch control relays IAN and 2AN, in addition to an exit relay; whereas, some of the other route establishing circuits, such as for' the route BD, include three switch control relays and with the same operating potential for all circuits, it is desirable to employ this compensating resistance 33, so that the same current flows through the switch control relays regardless; of "the number in series; The same scheme of including a compensating resistance is employed .in other route circuits, as may be required.

Rectifiers in circuit network-In the track layouts commonly used there are various arrangements of switches and crossovers which provide different routes between the same entrance and exit signal locations. Some of these alternative routes are useful or desirable options to. be used as required, and some are abnormal or undesired routes, such as a run-around movement over a pair of crossovers, as illustrated in Fig. 2. Also, from the standpoint of the circuit connections in a network suitable for energizing the normal or reverse switch'controlrelays for the various desirable routes, there are frequently difierent. conducting paths orpartial circuits for the flow of current through different switch control relays between common entrance and exit points; and since these circuit paths are in multiple and closed at the same time thereis a tendency to energize simultaneously the switch control relays for the normal or proper route and those foran abnormal or impossible route. Although such multiple circuit paths each include back contacts of relays in the other, and also generally include a different number of relays, so that the relays at these paths are energized with difierent current intensities, it is desirable to avoid any race or conflict in the energization of the relays for the proper route and for the impossible route. a

With these considerations in mind, in accordance with this invention rectifiers, preferably of the well-known copper-oxide type, are employed in the network at the appropriate points to allow the flow of current through the switch control relays for the routes desired, and blockthe flow of current throughthe switch control relays for other undesired routes, whether these undesired routes are optional, undesirable run-around movements over crossovers, orare impossible routes. I a I For example, referring to the track layout of Fig. 1, it can be seen that there are two desirable optional routes between the signal locations A and D, oneover the crossover normal and the crossover 2 reverse, and the other over crossover I reverse and crossover 2 normal. Either of these routes may be usedto advantage under certain conditions. This is a typical instance of useful optional routes; and provision is made as presently described for the manual and automatic selection between these optional routes, a rectifier being employed to block the flow of current through switch control relays that would interfere with such selection.

Referring to the track layout of Fig. 2, which is a typical arrangement of a pair of crossovers frequently found in practice, it can be seen that there are two possible routes between the signal locations L and N, one over the crossovers 1 and 8 in theirnormal positions, and the other ,a runaround movement over these crossovers'ieverse'. This run-around movement is one which is not ordinarily used, and there is no need for manual 'or automatic selection between these alternative routes. This is a typical example of possible but undesired routes which is adapted to the use of rectifiers'in the circuit network to prevent the improper 'energization of such control relays, as later explained more in detail.

' There is still'another situation with regard to what may be termedimpossible routes, that is, routes which a train cannot take, but which may .be established by the energization of normal or reverse switch control relays ina-circuit network.

Referring to the :track ilayoutpf Fig, :1,.;andconsidering the routes .between the signal flocations A and E, it can be seen that the circuit ,connec.- tions of the. network .tOZDIZDVidG .for the other ,desired routes terminating at said signal locations .gives,. in addition to theproper :route over crossover .I and switch .3 reverse, current conducting paths for .the energization :ofswitchrcontrol :relaysias if the train .could move from A to vE'over crossover I .normal,.crossover,2 :and switch} 'reverse. In other words, the circuit connections shown .in .Fig. 1 for providing .the various desired routes affords .a circuit path overrelays IAN, 2R, ZBN, 3N and .IBN :inmultiple with .relay .IR between the feed ;points.in the circuit energizedzzby theactuation of the buttons :ARB and EBB. This is atypical example of animpossible route which the circuit .network tends .to establish;.and. in accordance with. this invention, a rectifier AI is provided :andlpoled insuch a direction .as .to allow the .free how. of current through re.- lays LBN, ,3N.and ZBN for the route from -B .to Dbut block the flow of current through the abnormal circuit path above .noted.

Referring toFig. 2,.in whichthe control circuits for .the entrance .and exit-relays have beenomitted for the sake of simplicity, :it is evident that this network of Fig. .2 should provide for setting ,up routes between K and N and between Land M for both directions, but the .runearound movement over crossovers I and ,8 reverse .for train movement between L and Nshould :be avoided. For this reason, the rectifier 4 4 is included .in the route establishing circuit betweenK and M, this rectifier being poledin a direction to permit the flow of current in this circuit; and the connections 45 a d 46 for the u es and :K.-.N in the etworkaremade on opposite, sides .of this rectifier. Thus, the rectif er 44 blocks the flow of current through relays IR and r812, multiple with relays IBN and BBN when the buttons LIB d B a actua o ply opp s n pet .tials to the feed points for the route between L and N- The route establishing circuits for the routes between K and N and L and M include .rectifiers 41 .andfifi so poled that current may flow in these circuits for the desired route, but maynot flow th a wi c o tr rela fo m o s b e routes. The rectifier -51 blocks the flow of current through relays fiBN and ,BBN and {3R in mul- .tiple with the circuit through relay fI-B, when the route between L and M is set up; and similarly, the rectifier .48 blocks the flow of current in the circuit through relays IR, IBN, and BBN in mul .tiple with the proper path through relay 6B. for the route between K and N.

Thus, by the use ,of rectifiers in the manneregrermalii'ied by these typical examples, a network .with common feed points for the various routes to energize circuits through the switch control relays in series is provided, without obtaining an improper flow of current through switch control relays for impossible or undesired routes. This reducesthe number of contacts required at the feed points or other complications necessary to isolate the circuits or conducting paths for the authorized routes from the impossible or undesired routes.

OptionaZ route controL In many instances, the track layout provides two or more-optional routes between thesarne signal locations, both of which should be available as circumstances may require, In the track layout shown inFig. 1., for erample, there are tworoutes from .;A (to D,-o ne over the crossover normal Jand :the crossover 2 reverse, and the *OthBIgOYGI crossover reverse, and crossover 2 .normal;aud under some condi: tionsit may be more expedient to use one ofthese optional routes, and under. other conditions *the other route.

In the caseof such optional routes, @it is :proposed to provide an optional route lever gORL which, as it is moved from ,one position to the other, changes the connections of :the circuit hatwork to givea correspondinglonepf the two optional routes upon'actuation of the :buttons APB and 'DPB. *In the case assumed, with the optional route lever ,ORL in the position shown, and an optional route relayORR controlled thereby deenergized, this circuit network is in condition to set up the route A to D (or D .to A) over the crossover I normaland the crossover -2 reverse. If the operator actuates APB and DPB, under these conditions, the route establishing circuit is from through front contact .3] of relay ANR, relay 'I'AN, back contact ;3;2 ,of relay IR, resistance'33, back contact ,50 of relay ORR, back contact 5| of relay -2AN, relay--2R,;backcontact 52 of relay -2BN, back contact 31 of relay DNL, re lay DXR, and-contact 30 of button DPB,-,to The flow of current over the circuit'through re,- lays IR, IBN, 3N and 2BNJJ' .S' ,b lOCke d by the rectifier 42.

The route from A to D over-crossover I normal and crossover 2 reverse may be considered to be the preferred or superior route, since it would not conflict with the route -B to .E, which it might be desirable to use for some other train movement while the route :A to D is established. If,.however, the operator desires to use the inferior route from A to D ,over crossover I reverse, perhaps in anticipation of using the crossover 2 or a part of the Superior route for some subsequent train movement (assuming other switches or crossovers not shown are available for such purpose), he can do so by shifting the optional route button .ORL from the position shown to the other dotted position,.thereby energizing the optionalroutc relay ORR by a circuit from through lever ORL in dottedposition, relay ORR, back contact 53 ofrelay 2R, to Under these conditions, when the buttons APB and DPB are actuated, relays 1B,, 3N and 2BN are energized in series by a circuit from front contact .3 I of relay ANR, back contact 54 of relay IAN, relay IR, back contact 55 of .relay IBN, through the front contact 56 of relay ORR, relay 3N, back contact 51 of relayZR, relay ZBN, back contact 3 I of relay D NL, relay DXR, and contact 30 of button DPB, to while the circuit through relays IAN and 2B. is broken ;at the back contact 50 of this relay ORR.

The relay ORR. is preferably provided with a stick circuit through its own front contact :58 andthe front contact 59 of relay IR, so that it is maintained energizedso long as the inferior route establishing circuit is energized, and in dependently oi the. optional route lever ,ORL, so that the operator may;not break down suchinferior route after it is once established by operating lever ORL by mistake .or otherwise. The pick-up circuit for the optional'route relay ORR also preferably includes the back contact 53 of the relay 2R, so that if thesuperior route over the crossover 2 reverse. should be set up, "and the operator by mistake should move the optional route lever ORL, the relay .QRRgcannot be ,oper-, ated to breakdown the superior .route '{ES'tabe fished, J

In addition to the manual selection between optional routes, typically exemplified by the two alternative or optional routes from A to D, provision is also preferably made to shift automatically from the superior route normally in use to the other inferior route when some route in conflict with the superior route has been established, and the inferior route is the only one possible, this automatic shift avoiding the need for the operator to use the optional route lever ORL under such circumstances. Assume that the crossover 2 in its normal position is included in some route over a switch not shown which is not in conflict with the route from A to D over crossover I reverse, so that the superior route from A to D over crossover 2 reverse is not available on account of suchconflict, but the inferior route from A to D over crossover l reverse is available. Under such conditions, the energization of relay 2AN by the establishing of the conflicting route in question and the closing of its front'contact 60 energizes the relay ORR with the lever ORL in the normal position, thereby automatically shifting 'to the inferior route. The relay ORR, if once thus energized is stuck up through the front contact of relay IR in this inferior route, independently of the front contact 60 of the relay 2AN, so that this inferior route is maintained even after the conflict in question ceases.

.The optional route relay 'ORR is thus energized at the time a route is established on the upper track over the cross over 2 normal, on the assumption that this represents a condition where a route in conflict with the superior route exists and yetthe inferior route is available; but unless the inferior route is set up to energize relay IR, the optional route relay ORR drops back to its normal position when relay 2AN drops, and the superior route will then be the one subsequently obtained by the actuation of the buttons APB and DPB.

Double signal Zocations.In some instances in the various arrangements of track switches and signals encountered in practice, there may be two signals opposite one another at a signal location governing train movement in opposite directions; andsuch a signal location may constitute both an entrance point and an exit point for train movement in opposite directions.

In accordance with this invention, a special arrangement of relays and circuits is provided for such a signal location, in order that the same button may be employed to perform both the entrance and exit functions for both directions, although separate buttons may be used if desired. Such an arrangement is illustrated for the signal location C and its push button CPB in Fig. A. There is an entrance relay CNL for train movement to the left, and an entrance relay CNR for train movement to the right. Similarly, there are exit relays CXR and OX1; for train movement to the signal location C from the rightand from the left respectively.

If the operator sets up a route from A to C, the exitrelay CXR is energizedin the same manner previously explained upon actuation of the button CPB to close its contact 30a. In a sime ilar way, if the operator sets up a route from F to C, the exit relay CXL is energized through the contact 36b of the button CPB. In other words,.if the signal location C is used as-an exit point, some other button A or? will have been previously operated, and the operation resulting from the actuation of the button CPB is similar to that already explained, the possibility of the button CPB causing energization of an entrance relay CNL or CNR being prevented by the prevention means in.the same way already described.

When, however, the button CPB at the double signal location C is actuated to define the entrance point of a route, there are other operating conditions to be considered; and additional contacts are provided in the circuits to take care of the different contingencies. Assume, for instance, that the operator sets up the route from A to C for the movement of a train, and later wishes to advance this train over some other route from C, say to F. Under these conditions, the switch control relay 2AN is energized, and at the time the button CPB is operated, the pick-up bus PU is energized with positive potential, and the entrance relay CNR is energized over a circuit from the bus PU, back contact 6| of entrance relay CNL, contact l2b of the button, back contact 13 of relay CXL, front contact 62 of relay 2AN, lower winding of relay CNR, wire 63, back contact I4 of relay SAN, wire 64 through front contact l6 of track relay FTR, and contact I! of the button to The other entrance relay CNL is not energized under these conditions because its pick-up circuit is broken at the back contact 14 of the relay 2AN and also the front contact 62 of relay SAN.

When the button CPB, having been previously used to perform an exit function, is thus actuated for the second time for performing the entrance function for a new route, it can be seen that the exit relay CXR is already energized at the second time the button is actuated by reason of the first actuation of the button CPB for the route from A to C. To prevent the energization of relays QP and SL that would otherwise occur, the connection between the contact I2a of the button and the bus PU includes the back contact 6| of the entrance relay CNR. Consequently, when this relay CNR picks up upon the second operation of the button CPB, the connection between the bus CM and the bus PU is broken before there is time to energize relays Q, QP and SL, and restore the prevention means to the normal condition, thereby leaving the bus PU energized with the negative potential to prevent energization of an entrance relay by the subsequent operation of another button.

Under ordinary operating conditions, a route leading up to a double signal location, such as C, is necessarily established before and at the time the corresponding button CPB is actuated for the purpose of setting up some other route leading away from said signal location; and a switch control relay, such as relay 2AN, in the established route is energized to close its contact 62 in the pickup circuit for the proper entrance relay CNR, and open its back contact [4 in the energizing circuit for the other entrance relay. In this way, the successive operations of the same button CPB at a double signal location perform the desired entrance and exit functions.

In connection with this control of the energizing circuits for the entrance relays at a double signal location, it can be seen that in the case of the location C the track layout i such that the crossover 2 must be normal and relay 2AN energized for any route leading to the location C from the left; and similarly the crossover 5 must be normal and its relay 5AN energized for any route leading to the signal location C from the right. In other cases, as for example. at the signal location F in Fig. 5B, the track layout may be such that a crossover may be in either position for a route terminating at such location; and in this case the contacts of both the normal and reverse switch control relays of the adjacent crossovers are included in the energizing circuits for the entrance relays. For example, the pick-up circuit for the entrance relay FNL includes in multiple front contacts 62 and 52a of the relays BAN and SR, since the crossover 6 may be either in the normal or reverse position for train movement toward the signal location F. Similarly, the pick-up circuit for this entrance relay FNL includes in series back contacts I 4 and I5 of the relays 5AN and 5B.

The control of the entrance relays at a double signal location i such that the operator may make a switching movement as well as a straight through train movement. For example, assume the operator wishes to advance a train from C to F and then back from F to D. The first actuation of the button FPB, following operation of the button CPB, establishes the route from C to F, energizing the relay 5AN and exit relay FXR, but neither entrance relay is energized at this time while the button FPB is operated, because the bus PU is connected to the negative potential until the button is released to allow relay QP to drop, as previously explained. In order to advancethe train beyond the signal location F for the switching movement under consideration, button FPB is operated a second time and followed by operation of button I-IPB. When the button FPB is thus actuated the second time, the bus PU i connected to positive potential, and relay 5AN being energized, the entrance relay FNR is energized by a circuit similar to that previously described for the energization of entrance relay CNR; and upon actuation of the button HPB the route F--H is established and the righthand signal at F cleared for the train to move. In this connection, it should be understood that the relay SAN is stuck up while the train is in the route C-F by the operation of the relays and circuits illustrated in Fig. 10 and later explained. When the train passes the signal F, the entrance relay FNR is deenergized by the dropping of the track relay HTR, but the switch control relay SAN is stuck up. When the train clears the route CF, relay SAN drops; and

when under these conditions the button FPB is again actuated, the entrance relay FNL is energized, relay 5AN being down to close its back contact 14, and relay BAN being energized to close its front contact 62. DPB is subsequently operated for the desired switching movement, the route F to D is set up in the usual way, the left-hand signal at F clears, and the train may complete the desired switching movement.

If the operator should for any reason happen to operate the button CPB at a double signal location without having set up previously a route leading toward that location, neither entrance relay CNL or CNR is energized, because their respective pick-up circuits are broken at the open front contact 62 of the switch control relays ZAN and EAN. In other words, an abnormal or improper actuation of a button at a double signal location, prior to establishing a route for train movement up to that location, is an ineffective and idle manual operation, which does not produce any undesired control in its relays.

Through route operation-There are fre- When the button 4 quently situations in the various track layouts encountered in practice where through routes from one signal location past one or more other intermediate signal locations should be established for a through train movement; and while the operator can at any time set up routes through the track layout to any extent desired by operating in succession the buttons at the ends of the separate stretches or portions of track between adjacent signal locations, it is desirable to enable the operator to be able to establish such through routes past one or more signal locations by actuating only the buttons at the extreme ends of such through route. It is considered that the need for such through route manipulation is ordinarily confined to certain parts of the complete track layout, such as the through main tracks, or tracks into and out of station platforms, and similar situations; and since the facility for through route operation is provided to reduce the number of manual actuations'required of an operator, and is unnecessary unless the through route is commonly used, it is proposed in accordance with this invention to provide for through route operation for only such signal locations as desired by means of a separate circuit organization, including a through route relay for the intermediate signal location or locations in the desired through route.

The principles and mode of operation of the means for providing for through route operation are exemplified for the upper track in Figs. 5A and 5B, where through routes AF, A-H, or C--H may be set up at will by the operator, while at the same time permitting him to establish the routes AC, C--F, and F-H, individually at any time. For this purpose, through route relays CTl-IR and FTHR. are provided for the intermediate signal location 0' and F, and these through route relays are energized by the actuation of the buttons at the extreme ends of the through routes and produce at their respective intermediate signal locations the same controlling effect upon the route establishing circuit network as if their corresponding buttons CPB and FPB had "been operated in conjunction with the buttons at the entrance ends of the through route. These through route relays are of the usual neutral-polar type, and are energized for opposite polarities for opposite directions of train movement.

As a typical example of such through route operation, assume that the operator desires to set up a through route from A to F past the intermediate double signal location C. He first operates the button APB to pick up the entrance relay ANR, and then the button FPB; and assuming the parts in the normal condition with 1110 conflicting routes established, the through route relays CIHR is energized by a circuit which may be traced from contact $5 of button FPB, back contact 65 of exit relay FXR, back contact 6? of entrance relay FNL, wire 68, back contact 69 of exit relay CXL, back contact 10 of exit relay CXR, relay CTHR, back contacts H and W of relays 2R and IR, and front contact $1 of entrance relay ANR, to

In this way, the through route relay CTHR is energized with one polarity assumed to position its polar contacts to the left. The closing of the front contact 14 of this relay CTHR shunts the back contacts 69 and 10 of the exit relays CXL and CXR, so that said relay C'I'HR may be maintained energized independently of the energizati'on' of these-exit relays. The c-losure'of the "front contact "15 and polar contact" of the relay the route establishing circuit for route A to C; the

same. as if the button- CPB were manually actu- "ated subsequent'to the actuation of button APB. Relay CTHR also closes its'front contact 11; and "when the exit relay CXR picks up, the positive potential applied to the CM bus through the 'upperwinding of relays QPin series with the relay SL causes current to flow through the front "contact l3 of relay CXR, front "contact "of "relay CTHRyandback contact [3 of relay C'EGJ, "through theenergizingcircuit for the entrance relay CNR previously described.

In this way, the entrance relay CNR' is ener- "gized, and the "button'FPB being held down, the route establishing circuit for the route C to F, 'an'd'including the ex'itrelay FXR, is energized in the same manner "previously explained. The

energization of the exit relay FXR opens at its back con'tact 66 the energizing circuit "for the "through route relayCTI-IR, thereby causing that relay'to assume its normal deenergized condition, and whenthe'button FPB is released, the flow of current through relays QPandj SL ceases, whereupon the relay QP drops and applies the positive potential 'tothe pick-up bus PU, ready for the next operation,

"The operation for'establishing a through route in the other "direction from -F to Ais "similar to that just described. Int'his' case,the entrance relay'FNLis energized, and'when the button APB is actuated to close its contact 65, the

"through route relay CTHR is energized with the other polarity, thereby shunting by its neutral contact 18 and polar contact 19'the contact 3% 'of the'button 'CPB' to pick up the exit'relay CIGJ, v

which in turn causes energization' of the entrance relay CNL,'in the same mannerasdescribed, in

turn governing the energization of "the route establishing circuit network With button APB actuated to set upthe route'C-A.

The same plan of operation maybe employed for establishing through routespast two or more intermediate signal locations by arranging the circuits to provide for the 'energization of the through route relays at such locationsup'on 'ac- 'tuation of the buttonsat the extreme ends. Assume,'for instance, that'the'operator desires to set up a through route from A to H'pastthe intermediate signal locations C and 'F. 'In'this case, the through route relay CTHR isenergized by a circuit from (-1-), through the contact 65 of button HPB, back contact 66 of relay 'HXR,

'back contact 61 of "entrance relay HNL, back contact '80 of relay 6R, wire 8|, normally closed contact 65 of button FPB, back contact66 of contactstilarid T of exit relaysFXL and FXR,

relay FTHR, back contact82 ofrelay R, wire 83, back contact'fil o'f 'entra'ncerelay CNR, back contact'iifi of exit relay'CXL, normally closed, "contact "65 of button CPB, and'thence along the same circuit path previously traced to 'th' roughthe -contact 61 of the entrance relay "The 'ener'gization of relay FTHR' closes its "'neutralicontactliandi'shifts its polar contact 16 to "the "left, thereby shunting the contact "30a ayes-tan of the button-FPB, and permitting the establishfing of the route C-F'the-sa'measif button FPB had been actuated; and this is followed by the energization of the entrance relays FNR in the 5 same manner previously-explained for the energization of entrance relay CNR, whereupon the 'route- F-H is set up.

It can alsobe seen that actuation of the buttons CPB and 'HPB will cause energization of the through route relay FTHR and enable through 'routes-'C*-H or H--C to be established in ac- 'c'ordance with the same plan of operation 'fOr the through routes A'-F"and -FA. It is contempl'ated that the same organization of circuits l5 and plan of operation'will be provided for the '20 "shoul'd'be prevented when a part of the route has been individually established. For example, if

"the'operator has set up'the rout A--C, and then actuates-button FPBforthe purpose of setting uproutes F D,"F'-H'OI FI, the through route relay'CTHR should not be energized in such a case, otherwise the route C'F might be set up contrary to the wishes of the operator. For this reason, the back contacts 69 and 10 of the exit relays CXR and CXL are-included in the initial energizing "circuit 'for the relay CTHR; and in the case just stated, relay CTHR is not energized byactuation of button FPB with the entrance "relay 'ANRrup, because exit relay CXR is up on account of 'the' established route A-C. In other words, if the intermediate signal location such as C, constitutes the exit point of'a route already "established, and the exit relay CXR. and CXL for such location is energized, the through route relay CTHR- cannot be energized.

The energizingcircuits for the through route relays-also preferably include back contacts of certain'switch control relays. For example, the "energizing-circuit for CTHR. includes the back "contacts "H and 12 of the switch control relays 'l-Ran'd' 2R; If'any'route is established in conflict *route through-the track'layout by operation of the buttons at the ends of such routes, insofar as involves'the energization of the switch control relays; and the -entranceand exit relays,- consideration may now'be given to-the-Way-in which these relays control the operation of their asso-- -ciated track switches and the clearing of the signals.

-Fig. 3 illustrates in a simplified and diagram- 'matic manner one suitable organization of circuits for governing the operation of aswitch machine by its associated normal and reverseswitch control relayslN and IR; and it is contemplated that the same circuit organization will "beemmachines operating singleswitches or cross-overs in'thepomplete track layout.

The switch machine foroperating the locking and switch points -|TS isassumed to be of-the typical Wellknown construction, and-comprises "the usual motor 'Mand cut-off contacts*9fl,-with 'ployedfor'controlling the various other switch- .relay IL, relay ILS, to

suitable point detector contacts (not shown) for operating the switch repeater or position indicating relay IWP. The operating circuits for the switch machine motor are controlled by normal and reverse relays IWN and IWR; and the application of power to the switch machine, and the energization of the relays IWN and IWR is subject to a lock stick relay ILS, controlled by the detector track relay ATR and a lock relay IL. It is contemplated and assumed that the lock relay IL will form a part of a circuit organization suitable for providing the desired approach and rear release route locking, such as disclosed for example in the patent to O. H. Dicke, No. 2,045,900, June 30, 1936. Such approach and route locking circuits, with the necessary track circuit and time element release, form no part of the present invention; and while it should be understood that a suitable means of this character is to be employed, such locking means for the switch may take any suitable form, and has not been illustrated.

The operation of the switch. machine is primarily controlled by a neutral-polar relay IWZ, which in turn is governed in a suitable manner by the corresponding switch control relays IN and IR of the route establishing circuit network. In the simplified arrangement shown in Fig. 3, it is assumed that the relay IW Z is directly controlled over a line circuit by the relays IN and IR.

As a typical example of the operation of the switch control circuits of Fig. 3, assume that the switch points are to be operated from the normal position shown to the reverse position. If the detector track section is not occupied, or the lock relay IL deenergized, so that the switch machine may be properly operated, the lock stick relay ILS is energized by a circuit from through back contact 9I of relay IWZ, front contact 92 of track relay ATR, front contact 93 of The switch repeater relay IWP is also energized to position its polar contacts to the right. When the switch control relay IR is energized to reverse the switch, relay IWZ is energized from one terminal (B) of a split battery to back contact 94 of relay IN, front contact 95 of relay IR, line wire 96, relay IWZ to (CN), indicating the midtap of such a battery. This energization of the relay IWZ closes its neutral front contacts and positions its polar contact to the left. Since the polar contact 9! moves to the left-hand position before the neutral contact 9I opens its back contact in the pick-up circuit for relay ILS, the correspondence relay INCR is not even momentarily energized, and the lock stick relay ILS is held up by its stick circuit through its front contact 98 and the back contacts 99, I99 of the correspondence relays INCR and IRCR. With the lock stick relay ILS energized and its front contact IDI closed, the energization of relay IWZ establishes an energizing circuit for relay IWR through front contact I02 of relay IWZ and its polar contact I03 to the left. This operation of the relay IWR closes the reverse operating circuit for the switch machine motor, and causes the switch machine to operate to its reverse position in the well known manner. Inthis connection, it will be noted that the operating circuits for the switch machine motor include front contacts I99 and I95 of lock stick relay ILS, so that no power can be applied to the switch machine when this lock stick relay isdeenergized.

When the switch machine assumes its over and locked reverse position, the contacts 99 shift and trance-exit operation,

open the motor circuit; and the relay IWP is energized with its polar contact In! to the left. This establishes an energizing circuit for the correspondence relay IRCR through front contact I06 of relay IWP, its polar contact Illl to the left, relay IRCR, polar contact 91 of relay IWZ to the left, and neutral contact 9| of this relay. The resultant energization of the correspondence relay IRCR breaks at its back contact 99 the stick circuit for the lock stick relay ILS, and its pick-up circuit being broken at the back contact 9| of relay IWZ, this lock stick relay drops to cut off power from the switch machine, to deenergize relays IWN and IWR, and further close contacts of the signal clearing circuit later to be explained. In other words, when the switch machine completes its intended cycle of operation, the lock stick relay ILS is deenergized to prevent operation of the switch to the other position; and this desired locking of the switch occurs before a signal can be cleared for train movement over the switch.

In connection with the display of indications on the control panel, as later described, it is desirable to indicate the position and locked condition of each switch or crossover of the track layout in the control office; and in the simplified arrangement shown in Fig. 3, the relay IWP con- .trols the energization of repeater relays IWNP and IWRP in the control office over line circuits by the closing of the neutral and polar contacts I98 and I99 of this relay IWP.

There may be occasions where it is desirable forthe operator to cause the power operation of a switch from one position to the other, without clearing a signal. For example, it may be expedient to move a switch back and forth to clear it of an obstruction, to keep it clear of snow, to facilitate maintenance Or repair, or the like. Accordingly, auxiliary or emergency individual switch levers SML are preferably provided on the control panel for governing the energization of the corresponding relay WZ, independently of the switch control relays N and R of the route establishing circuit network. Fig. 3 illustrates how such an auxiliary switch lever ISML is preferably connected through the back contacts I II] and of relays IN and IR to the control circuit for relay IWZ, movement of this lever to one extreme position or the other energizing the relay IWZ with currents of opposite polarities to cause corresponding operation of the switch machine. It will be noted thatthis auxiliary lever ISML is not effective unless the corresponding switch control relays IN and IR are both deenergized. In other words, if a route has been established by an encareless or accidental movement by the operator of the auxiliary switch lever for any of the switches involved in that route will not break down this route.

Signal c0-ntr0l.It is contemplated that the signals, governing train movement over the various routes and shown diagrammatically in the accompanying drawings, will be multiple aspect semaphore or color-light signals of the type commonly used in interlocking practice, and will be provided with suitable control circuits in accordance with established practice to give the desired indications. In the various forms of signal control circuit organizations suitable for governing train movement over the various routes of a track layout in accordance with this invention, there is usually a relay or relays for each signal which constitutes the primary controlling agency to cause that signal to display the appropriate .Referring to Fig. 3,;the energization of the en- ,tranceand exit relays, suchas ANR'and AXR, for each signal governs the energization of a neutral-polar signal control relay AGZ:over a direct or unit-wire connection III, or the like, as

will be. apparent from the drawings. Fig. 4 shows 1 1' how these signal control relays GZ, in co-operation with the track relays, switch correspondence relays, and lock stick relays, operate to govern the energization of the corresponding .signal clearing relay GHIR. It would appear to be unnecessary to trace and explain the circuits for all of the yarious signals and routes, since these are organized on the .same plan, .and'an explanation of these circuits for the control route is typical of all of the. others.

Referring to Fig. 4, and considering the route between A and C, when this route is set up. in thecontrol ofi'ice by the energization of'the entrance relays -ANR and the exit relay CXR, the 'energization of the relay ANR causes energization of the corresponding relay AGZ (see Fig. 3) to position its polar contact M to the right, and similarly the energization of relay CXR operates thepolar contact H5 of its associated relay CGZ to .the left. .ing the track sections AT and CT unoccupied, thecrossovers I and 2 in the normal position, and the lock stick relays ILS and 2LS for thesetcross rovers deenergized, the circuit to energize the signal clearing relay AGI-IR for causing the associated signal AG to display a suitable proceed. indication may be traced from relay AGHR, ,polar contact II5 of relay AGZ to the right, its neutralcontact H6, contact II! of track relay ATR, front contact IE3 of the normal :correspondence-relay INCR for the crossover:I ,.:back :contact II9 of lock stick relay ILS,i'front contact 120 of track relay CTR, back contactIZI of lock stick relay 2LS, front contact I22 of normal. correspondence relay ZNCR, front neutral contact .II-6 of relay CGZ, and its polar contact II5'to the left, to

Ifthe same route between C and A is established by energization of the entrance relay CNL and the exit relay AXL, the. relay CGH-R for the.

signal C is energized by a circuit similar to the one just traced through the polar contact H5 of relay .CGZ to the right and the polar contact :II5 of relay AGZ to the left. The circuits for governing the clearing of the other signals for otherroutes are similar to those just described, and need not be individually discussed.

This arrangement ofcircuits utilizes the same --contacts on the switch correspondence relays, track relays,andlock relays for the various-routes -in-such a way as to reduce thenumber of relays and contacts required'to obtain the necessary selection of the signal control circuitsfor opposite directions of train movement and forthedif- "ferent positions of the switches.

Displayo indiccztio'rzs.-The desired visual incdieati-ons on the control panel for the information ofthe operator may be displayed in various ways;

ibutin the interests of-simplicity and economy in I, space on the controlpanehthese indications are Under these conditions, and assuml ape-5349 preferably displayed .by lighting various miniature lamps as illustrated diagrammatically in Figs, 6 tolO.

In connection with .theseindicatio-ns, since :the buttons by which the switches and signalsare governed forithe variousroutes are self-restoring and. do not show by their-position what routes have been attempted'or completed, itis important .in the entrance-exit type of system characterizing this invention toprovide on the track diagram suitable indications to show the routes attempted .and established, together with suitable indications .of .the operated position of the track switches andJtrack occupancy, in order that the operatorimay have adequate information to guide himsinhis manipulation; and for this purpose various miniature lamps are provided on the track diagram and controlled by an organization of circuitsshown inFigs. 9 .and 10 to visually display this indication in ;an. eliective and arrestive manner whichxthe operator can easily understand and interpret.

Referring to Figs. 7 and .8, :which are fragmentarysections illustrating certain constructional features of .the control .panel and visual indicating .means, the panel preferably comprises a :metal supporting plate I25 with holes therein to receive the push buttons APB, BPB, etc., and at the various points where the indicating lamps should belocated to conform with the particular track layout. The linesof the trackv are represented on the panel by-strips or bars of I glass I26 and'adjoining spacers or connectingpiecesIZI of a-suitab-le opaque material,

which are preferably held in place on the face of the metalplate I25 (see Fig. 8) by blocks or strips I28 oftheappropriate shape fastened to the panel plate by screws I29 or the like, the

edges of the glass strips I26 and ad-joiningspacer pieces -I2I :being preferably beveled as shown and provided with a yieldable gasket I30 of suit- I able material.

Behind each of the glassstrips I26 is secured a lamp socket I 3| comprising a cylindrical shaped "housing of a-suita-ble moulded plastic material, fiber, orthe like, which carries contact springs I32, with the ends thereof constituting soldering tips for attaching wires, with which the base of a miniature lamp-I33 of the'usual type and construction engages. This socket I3I is formed with a base having adetachable bayonnet-type connection with ears or flanges of'a-ring I34 fastened to the back of the metal plate, preferably by spot welding as indicated at I35.

break up this internalreflection, so to speak, and give the whole glass strips the effect of a lighted strip or streak when the lamp I33 is lighted.

The various glass strips I26 are of such lengthand arranged with theiradjoining spacer pieces I21 in accordance-with the track layout, as shown in-Figs. 6 for the same track layout of Figs. 1 'and l, sothat there is a bar or strip,

' such as .AK, adjacent each signal location, other 'barsor strips such as IANK and I-RK for the normal and-the reverse "position of each switch "or'crossover, andother intermediate bars, such as XK, for such portions of track between the switches" necessarytogive the effect of -a sub- "stantially continuous line or streak oflight. The 

